Rising Scores on Intelligence Tests

All over the world, average scores on intelligence tests have been rising for the better part of a century—essentially ever since such tests were invented. For example, average scores on standard broad-spectrum IQ tests are going up by about three points-relative to a mean of 100—every 10 years, and the increases are even higher on specialized measures of abstract-reasoning ability. The cause of these enormous gains remains unknown. No one knows if they reflect genuine increases in intelligence or just a gradual spread of some specialized knack for taking tests. Greater sophistication about tests surely plays some role in the rise, and other possible contributing factors include better nutrition, more schooling, altered child-rearing practices and the technology-driven changes of culture itself. Neisser explores these factors, and concludes that our highly visual environment may play a fundamental role in the increases in IQ scores.